xref: /qemu/hw/arm/boot.c (revision bfa3ab61)
1 /*
2  * ARM kernel loader.
3  *
4  * Copyright (c) 2006-2007 CodeSourcery.
5  * Written by Paul Brook
6  *
7  * This code is licensed under the GPL.
8  */
9 
10 #include "config.h"
11 #include "hw/hw.h"
12 #include "hw/arm/arm.h"
13 #include "sysemu/sysemu.h"
14 #include "hw/boards.h"
15 #include "hw/loader.h"
16 #include "elf.h"
17 #include "sysemu/device_tree.h"
18 #include "qemu/config-file.h"
19 #include "exec/address-spaces.h"
20 
21 /* Kernel boot protocol is specified in the kernel docs
22  * Documentation/arm/Booting and Documentation/arm64/booting.txt
23  * They have different preferred image load offsets from system RAM base.
24  */
25 #define KERNEL_ARGS_ADDR 0x100
26 #define KERNEL_LOAD_ADDR 0x00010000
27 #define KERNEL64_LOAD_ADDR 0x00080000
28 
29 typedef enum {
30     FIXUP_NONE = 0,   /* do nothing */
31     FIXUP_TERMINATOR, /* end of insns */
32     FIXUP_BOARDID,    /* overwrite with board ID number */
33     FIXUP_ARGPTR,     /* overwrite with pointer to kernel args */
34     FIXUP_ENTRYPOINT, /* overwrite with kernel entry point */
35     FIXUP_GIC_CPU_IF, /* overwrite with GIC CPU interface address */
36     FIXUP_BOOTREG,    /* overwrite with boot register address */
37     FIXUP_DSB,        /* overwrite with correct DSB insn for cpu */
38     FIXUP_MAX,
39 } FixupType;
40 
41 typedef struct ARMInsnFixup {
42     uint32_t insn;
43     FixupType fixup;
44 } ARMInsnFixup;
45 
46 static const ARMInsnFixup bootloader_aarch64[] = {
47     { 0x580000c0 }, /* ldr x0, arg ; Load the lower 32-bits of DTB */
48     { 0xaa1f03e1 }, /* mov x1, xzr */
49     { 0xaa1f03e2 }, /* mov x2, xzr */
50     { 0xaa1f03e3 }, /* mov x3, xzr */
51     { 0x58000084 }, /* ldr x4, entry ; Load the lower 32-bits of kernel entry */
52     { 0xd61f0080 }, /* br x4      ; Jump to the kernel entry point */
53     { 0, FIXUP_ARGPTR }, /* arg: .word @DTB Lower 32-bits */
54     { 0 }, /* .word @DTB Higher 32-bits */
55     { 0, FIXUP_ENTRYPOINT }, /* entry: .word @Kernel Entry Lower 32-bits */
56     { 0 }, /* .word @Kernel Entry Higher 32-bits */
57     { 0, FIXUP_TERMINATOR }
58 };
59 
60 /* The worlds second smallest bootloader.  Set r0-r2, then jump to kernel.  */
61 static const ARMInsnFixup bootloader[] = {
62     { 0xe3a00000 }, /* mov     r0, #0 */
63     { 0xe59f1004 }, /* ldr     r1, [pc, #4] */
64     { 0xe59f2004 }, /* ldr     r2, [pc, #4] */
65     { 0xe59ff004 }, /* ldr     pc, [pc, #4] */
66     { 0, FIXUP_BOARDID },
67     { 0, FIXUP_ARGPTR },
68     { 0, FIXUP_ENTRYPOINT },
69     { 0, FIXUP_TERMINATOR }
70 };
71 
72 /* Handling for secondary CPU boot in a multicore system.
73  * Unlike the uniprocessor/primary CPU boot, this is platform
74  * dependent. The default code here is based on the secondary
75  * CPU boot protocol used on realview/vexpress boards, with
76  * some parameterisation to increase its flexibility.
77  * QEMU platform models for which this code is not appropriate
78  * should override write_secondary_boot and secondary_cpu_reset_hook
79  * instead.
80  *
81  * This code enables the interrupt controllers for the secondary
82  * CPUs and then puts all the secondary CPUs into a loop waiting
83  * for an interprocessor interrupt and polling a configurable
84  * location for the kernel secondary CPU entry point.
85  */
86 #define DSB_INSN 0xf57ff04f
87 #define CP15_DSB_INSN 0xee070f9a /* mcr cp15, 0, r0, c7, c10, 4 */
88 
89 static const ARMInsnFixup smpboot[] = {
90     { 0xe59f2028 }, /* ldr r2, gic_cpu_if */
91     { 0xe59f0028 }, /* ldr r0, bootreg_addr */
92     { 0xe3a01001 }, /* mov r1, #1 */
93     { 0xe5821000 }, /* str r1, [r2] - set GICC_CTLR.Enable */
94     { 0xe3a010ff }, /* mov r1, #0xff */
95     { 0xe5821004 }, /* str r1, [r2, 4] - set GIC_PMR.Priority to 0xff */
96     { 0, FIXUP_DSB },   /* dsb */
97     { 0xe320f003 }, /* wfi */
98     { 0xe5901000 }, /* ldr     r1, [r0] */
99     { 0xe1110001 }, /* tst     r1, r1 */
100     { 0x0afffffb }, /* beq     <wfi> */
101     { 0xe12fff11 }, /* bx      r1 */
102     { 0, FIXUP_GIC_CPU_IF }, /* gic_cpu_if: .word 0x.... */
103     { 0, FIXUP_BOOTREG }, /* bootreg_addr: .word 0x.... */
104     { 0, FIXUP_TERMINATOR }
105 };
106 
107 static void write_bootloader(const char *name, hwaddr addr,
108                              const ARMInsnFixup *insns, uint32_t *fixupcontext)
109 {
110     /* Fix up the specified bootloader fragment and write it into
111      * guest memory using rom_add_blob_fixed(). fixupcontext is
112      * an array giving the values to write in for the fixup types
113      * which write a value into the code array.
114      */
115     int i, len;
116     uint32_t *code;
117 
118     len = 0;
119     while (insns[len].fixup != FIXUP_TERMINATOR) {
120         len++;
121     }
122 
123     code = g_new0(uint32_t, len);
124 
125     for (i = 0; i < len; i++) {
126         uint32_t insn = insns[i].insn;
127         FixupType fixup = insns[i].fixup;
128 
129         switch (fixup) {
130         case FIXUP_NONE:
131             break;
132         case FIXUP_BOARDID:
133         case FIXUP_ARGPTR:
134         case FIXUP_ENTRYPOINT:
135         case FIXUP_GIC_CPU_IF:
136         case FIXUP_BOOTREG:
137         case FIXUP_DSB:
138             insn = fixupcontext[fixup];
139             break;
140         default:
141             abort();
142         }
143         code[i] = tswap32(insn);
144     }
145 
146     rom_add_blob_fixed(name, code, len * sizeof(uint32_t), addr);
147 
148     g_free(code);
149 }
150 
151 static void default_write_secondary(ARMCPU *cpu,
152                                     const struct arm_boot_info *info)
153 {
154     uint32_t fixupcontext[FIXUP_MAX];
155 
156     fixupcontext[FIXUP_GIC_CPU_IF] = info->gic_cpu_if_addr;
157     fixupcontext[FIXUP_BOOTREG] = info->smp_bootreg_addr;
158     if (arm_feature(&cpu->env, ARM_FEATURE_V7)) {
159         fixupcontext[FIXUP_DSB] = DSB_INSN;
160     } else {
161         fixupcontext[FIXUP_DSB] = CP15_DSB_INSN;
162     }
163 
164     write_bootloader("smpboot", info->smp_loader_start,
165                      smpboot, fixupcontext);
166 }
167 
168 static void default_reset_secondary(ARMCPU *cpu,
169                                     const struct arm_boot_info *info)
170 {
171     CPUARMState *env = &cpu->env;
172 
173     address_space_stl_notdirty(&address_space_memory, info->smp_bootreg_addr,
174                                0, MEMTXATTRS_UNSPECIFIED, NULL);
175     env->regs[15] = info->smp_loader_start;
176 }
177 
178 static inline bool have_dtb(const struct arm_boot_info *info)
179 {
180     return info->dtb_filename || info->get_dtb;
181 }
182 
183 #define WRITE_WORD(p, value) do { \
184     address_space_stl_notdirty(&address_space_memory, p, value, \
185                                MEMTXATTRS_UNSPECIFIED, NULL);  \
186     p += 4;                       \
187 } while (0)
188 
189 static void set_kernel_args(const struct arm_boot_info *info)
190 {
191     int initrd_size = info->initrd_size;
192     hwaddr base = info->loader_start;
193     hwaddr p;
194 
195     p = base + KERNEL_ARGS_ADDR;
196     /* ATAG_CORE */
197     WRITE_WORD(p, 5);
198     WRITE_WORD(p, 0x54410001);
199     WRITE_WORD(p, 1);
200     WRITE_WORD(p, 0x1000);
201     WRITE_WORD(p, 0);
202     /* ATAG_MEM */
203     /* TODO: handle multiple chips on one ATAG list */
204     WRITE_WORD(p, 4);
205     WRITE_WORD(p, 0x54410002);
206     WRITE_WORD(p, info->ram_size);
207     WRITE_WORD(p, info->loader_start);
208     if (initrd_size) {
209         /* ATAG_INITRD2 */
210         WRITE_WORD(p, 4);
211         WRITE_WORD(p, 0x54420005);
212         WRITE_WORD(p, info->initrd_start);
213         WRITE_WORD(p, initrd_size);
214     }
215     if (info->kernel_cmdline && *info->kernel_cmdline) {
216         /* ATAG_CMDLINE */
217         int cmdline_size;
218 
219         cmdline_size = strlen(info->kernel_cmdline);
220         cpu_physical_memory_write(p + 8, info->kernel_cmdline,
221                                   cmdline_size + 1);
222         cmdline_size = (cmdline_size >> 2) + 1;
223         WRITE_WORD(p, cmdline_size + 2);
224         WRITE_WORD(p, 0x54410009);
225         p += cmdline_size * 4;
226     }
227     if (info->atag_board) {
228         /* ATAG_BOARD */
229         int atag_board_len;
230         uint8_t atag_board_buf[0x1000];
231 
232         atag_board_len = (info->atag_board(info, atag_board_buf) + 3) & ~3;
233         WRITE_WORD(p, (atag_board_len + 8) >> 2);
234         WRITE_WORD(p, 0x414f4d50);
235         cpu_physical_memory_write(p, atag_board_buf, atag_board_len);
236         p += atag_board_len;
237     }
238     /* ATAG_END */
239     WRITE_WORD(p, 0);
240     WRITE_WORD(p, 0);
241 }
242 
243 static void set_kernel_args_old(const struct arm_boot_info *info)
244 {
245     hwaddr p;
246     const char *s;
247     int initrd_size = info->initrd_size;
248     hwaddr base = info->loader_start;
249 
250     /* see linux/include/asm-arm/setup.h */
251     p = base + KERNEL_ARGS_ADDR;
252     /* page_size */
253     WRITE_WORD(p, 4096);
254     /* nr_pages */
255     WRITE_WORD(p, info->ram_size / 4096);
256     /* ramdisk_size */
257     WRITE_WORD(p, 0);
258 #define FLAG_READONLY	1
259 #define FLAG_RDLOAD	4
260 #define FLAG_RDPROMPT	8
261     /* flags */
262     WRITE_WORD(p, FLAG_READONLY | FLAG_RDLOAD | FLAG_RDPROMPT);
263     /* rootdev */
264     WRITE_WORD(p, (31 << 8) | 0);	/* /dev/mtdblock0 */
265     /* video_num_cols */
266     WRITE_WORD(p, 0);
267     /* video_num_rows */
268     WRITE_WORD(p, 0);
269     /* video_x */
270     WRITE_WORD(p, 0);
271     /* video_y */
272     WRITE_WORD(p, 0);
273     /* memc_control_reg */
274     WRITE_WORD(p, 0);
275     /* unsigned char sounddefault */
276     /* unsigned char adfsdrives */
277     /* unsigned char bytes_per_char_h */
278     /* unsigned char bytes_per_char_v */
279     WRITE_WORD(p, 0);
280     /* pages_in_bank[4] */
281     WRITE_WORD(p, 0);
282     WRITE_WORD(p, 0);
283     WRITE_WORD(p, 0);
284     WRITE_WORD(p, 0);
285     /* pages_in_vram */
286     WRITE_WORD(p, 0);
287     /* initrd_start */
288     if (initrd_size) {
289         WRITE_WORD(p, info->initrd_start);
290     } else {
291         WRITE_WORD(p, 0);
292     }
293     /* initrd_size */
294     WRITE_WORD(p, initrd_size);
295     /* rd_start */
296     WRITE_WORD(p, 0);
297     /* system_rev */
298     WRITE_WORD(p, 0);
299     /* system_serial_low */
300     WRITE_WORD(p, 0);
301     /* system_serial_high */
302     WRITE_WORD(p, 0);
303     /* mem_fclk_21285 */
304     WRITE_WORD(p, 0);
305     /* zero unused fields */
306     while (p < base + KERNEL_ARGS_ADDR + 256 + 1024) {
307         WRITE_WORD(p, 0);
308     }
309     s = info->kernel_cmdline;
310     if (s) {
311         cpu_physical_memory_write(p, s, strlen(s) + 1);
312     } else {
313         WRITE_WORD(p, 0);
314     }
315 }
316 
317 /**
318  * load_dtb() - load a device tree binary image into memory
319  * @addr:       the address to load the image at
320  * @binfo:      struct describing the boot environment
321  * @addr_limit: upper limit of the available memory area at @addr
322  *
323  * Load a device tree supplied by the machine or by the user  with the
324  * '-dtb' command line option, and put it at offset @addr in target
325  * memory.
326  *
327  * If @addr_limit contains a meaningful value (i.e., it is strictly greater
328  * than @addr), the device tree is only loaded if its size does not exceed
329  * the limit.
330  *
331  * Returns: the size of the device tree image on success,
332  *          0 if the image size exceeds the limit,
333  *          -1 on errors.
334  *
335  * Note: Must not be called unless have_dtb(binfo) is true.
336  */
337 static int load_dtb(hwaddr addr, const struct arm_boot_info *binfo,
338                     hwaddr addr_limit)
339 {
340     void *fdt = NULL;
341     int size, rc;
342     uint32_t acells, scells;
343 
344     if (binfo->dtb_filename) {
345         char *filename;
346         filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, binfo->dtb_filename);
347         if (!filename) {
348             fprintf(stderr, "Couldn't open dtb file %s\n", binfo->dtb_filename);
349             goto fail;
350         }
351 
352         fdt = load_device_tree(filename, &size);
353         if (!fdt) {
354             fprintf(stderr, "Couldn't open dtb file %s\n", filename);
355             g_free(filename);
356             goto fail;
357         }
358         g_free(filename);
359     } else {
360         fdt = binfo->get_dtb(binfo, &size);
361         if (!fdt) {
362             fprintf(stderr, "Board was unable to create a dtb blob\n");
363             goto fail;
364         }
365     }
366 
367     if (addr_limit > addr && size > (addr_limit - addr)) {
368         /* Installing the device tree blob at addr would exceed addr_limit.
369          * Whether this constitutes failure is up to the caller to decide,
370          * so just return 0 as size, i.e., no error.
371          */
372         g_free(fdt);
373         return 0;
374     }
375 
376     acells = qemu_fdt_getprop_cell(fdt, "/", "#address-cells");
377     scells = qemu_fdt_getprop_cell(fdt, "/", "#size-cells");
378     if (acells == 0 || scells == 0) {
379         fprintf(stderr, "dtb file invalid (#address-cells or #size-cells 0)\n");
380         goto fail;
381     }
382 
383     if (scells < 2 && binfo->ram_size >= (1ULL << 32)) {
384         /* This is user error so deserves a friendlier error message
385          * than the failure of setprop_sized_cells would provide
386          */
387         fprintf(stderr, "qemu: dtb file not compatible with "
388                 "RAM size > 4GB\n");
389         goto fail;
390     }
391 
392     rc = qemu_fdt_setprop_sized_cells(fdt, "/memory", "reg",
393                                       acells, binfo->loader_start,
394                                       scells, binfo->ram_size);
395     if (rc < 0) {
396         fprintf(stderr, "couldn't set /memory/reg\n");
397         goto fail;
398     }
399 
400     if (binfo->kernel_cmdline && *binfo->kernel_cmdline) {
401         rc = qemu_fdt_setprop_string(fdt, "/chosen", "bootargs",
402                                      binfo->kernel_cmdline);
403         if (rc < 0) {
404             fprintf(stderr, "couldn't set /chosen/bootargs\n");
405             goto fail;
406         }
407     }
408 
409     if (binfo->initrd_size) {
410         rc = qemu_fdt_setprop_cell(fdt, "/chosen", "linux,initrd-start",
411                                    binfo->initrd_start);
412         if (rc < 0) {
413             fprintf(stderr, "couldn't set /chosen/linux,initrd-start\n");
414             goto fail;
415         }
416 
417         rc = qemu_fdt_setprop_cell(fdt, "/chosen", "linux,initrd-end",
418                                    binfo->initrd_start + binfo->initrd_size);
419         if (rc < 0) {
420             fprintf(stderr, "couldn't set /chosen/linux,initrd-end\n");
421             goto fail;
422         }
423     }
424 
425     if (binfo->modify_dtb) {
426         binfo->modify_dtb(binfo, fdt);
427     }
428 
429     qemu_fdt_dumpdtb(fdt, size);
430 
431     /* Put the DTB into the memory map as a ROM image: this will ensure
432      * the DTB is copied again upon reset, even if addr points into RAM.
433      */
434     rom_add_blob_fixed("dtb", fdt, size, addr);
435 
436     g_free(fdt);
437 
438     return size;
439 
440 fail:
441     g_free(fdt);
442     return -1;
443 }
444 
445 static void do_cpu_reset(void *opaque)
446 {
447     ARMCPU *cpu = opaque;
448     CPUARMState *env = &cpu->env;
449     const struct arm_boot_info *info = env->boot_info;
450 
451     cpu_reset(CPU(cpu));
452     if (info) {
453         if (!info->is_linux) {
454             /* Jump to the entry point.  */
455             if (env->aarch64) {
456                 env->pc = info->entry;
457             } else {
458                 env->regs[15] = info->entry & 0xfffffffe;
459                 env->thumb = info->entry & 1;
460             }
461         } else {
462             /* If we are booting Linux then we need to check whether we are
463              * booting into secure or non-secure state and adjust the state
464              * accordingly.  Out of reset, ARM is defined to be in secure state
465              * (SCR.NS = 0), we change that here if non-secure boot has been
466              * requested.
467              */
468             if (arm_feature(env, ARM_FEATURE_EL3)) {
469                 /* AArch64 is defined to come out of reset into EL3 if enabled.
470                  * If we are booting Linux then we need to adjust our EL as
471                  * Linux expects us to be in EL2 or EL1.  AArch32 resets into
472                  * SVC, which Linux expects, so no privilege/exception level to
473                  * adjust.
474                  */
475                 if (env->aarch64) {
476                     if (arm_feature(env, ARM_FEATURE_EL2)) {
477                         env->pstate = PSTATE_MODE_EL2h;
478                     } else {
479                         env->pstate = PSTATE_MODE_EL1h;
480                     }
481                 }
482 
483                 /* Set to non-secure if not a secure boot */
484                 if (!info->secure_boot) {
485                     /* Linux expects non-secure state */
486                     env->cp15.scr_el3 |= SCR_NS;
487                 }
488             }
489 
490             if (CPU(cpu) == first_cpu) {
491                 if (env->aarch64) {
492                     env->pc = info->loader_start;
493                 } else {
494                     env->regs[15] = info->loader_start;
495                 }
496 
497                 if (!have_dtb(info)) {
498                     if (old_param) {
499                         set_kernel_args_old(info);
500                     } else {
501                         set_kernel_args(info);
502                     }
503                 }
504             } else {
505                 info->secondary_cpu_reset_hook(cpu, info);
506             }
507         }
508     }
509 }
510 
511 /**
512  * load_image_to_fw_cfg() - Load an image file into an fw_cfg entry identified
513  *                          by key.
514  * @fw_cfg:         The firmware config instance to store the data in.
515  * @size_key:       The firmware config key to store the size of the loaded
516  *                  data under, with fw_cfg_add_i32().
517  * @data_key:       The firmware config key to store the loaded data under,
518  *                  with fw_cfg_add_bytes().
519  * @image_name:     The name of the image file to load. If it is NULL, the
520  *                  function returns without doing anything.
521  * @try_decompress: Whether the image should be decompressed (gunzipped) before
522  *                  adding it to fw_cfg. If decompression fails, the image is
523  *                  loaded as-is.
524  *
525  * In case of failure, the function prints an error message to stderr and the
526  * process exits with status 1.
527  */
528 static void load_image_to_fw_cfg(FWCfgState *fw_cfg, uint16_t size_key,
529                                  uint16_t data_key, const char *image_name,
530                                  bool try_decompress)
531 {
532     size_t size = -1;
533     uint8_t *data;
534 
535     if (image_name == NULL) {
536         return;
537     }
538 
539     if (try_decompress) {
540         size = load_image_gzipped_buffer(image_name,
541                                          LOAD_IMAGE_MAX_GUNZIP_BYTES, &data);
542     }
543 
544     if (size == (size_t)-1) {
545         gchar *contents;
546         gsize length;
547 
548         if (!g_file_get_contents(image_name, &contents, &length, NULL)) {
549             fprintf(stderr, "failed to load \"%s\"\n", image_name);
550             exit(1);
551         }
552         size = length;
553         data = (uint8_t *)contents;
554     }
555 
556     fw_cfg_add_i32(fw_cfg, size_key, size);
557     fw_cfg_add_bytes(fw_cfg, data_key, data, size);
558 }
559 
560 static void arm_load_kernel_notify(Notifier *notifier, void *data)
561 {
562     CPUState *cs;
563     int kernel_size;
564     int initrd_size;
565     int is_linux = 0;
566     uint64_t elf_entry, elf_low_addr, elf_high_addr;
567     int elf_machine;
568     hwaddr entry, kernel_load_offset;
569     int big_endian;
570     static const ARMInsnFixup *primary_loader;
571     ArmLoadKernelNotifier *n = DO_UPCAST(ArmLoadKernelNotifier,
572                                          notifier, notifier);
573     ARMCPU *cpu = n->cpu;
574     struct arm_boot_info *info =
575         container_of(n, struct arm_boot_info, load_kernel_notifier);
576 
577     /* Load the kernel.  */
578     if (!info->kernel_filename || info->firmware_loaded) {
579 
580         if (have_dtb(info)) {
581             /* If we have a device tree blob, but no kernel to supply it to (or
582              * the kernel is supposed to be loaded by the bootloader), copy the
583              * DTB to the base of RAM for the bootloader to pick up.
584              */
585             if (load_dtb(info->loader_start, info, 0) < 0) {
586                 exit(1);
587             }
588         }
589 
590         if (info->kernel_filename) {
591             FWCfgState *fw_cfg;
592             bool try_decompressing_kernel;
593 
594             fw_cfg = fw_cfg_find();
595             try_decompressing_kernel = arm_feature(&cpu->env,
596                                                    ARM_FEATURE_AARCH64);
597 
598             /* Expose the kernel, the command line, and the initrd in fw_cfg.
599              * We don't process them here at all, it's all left to the
600              * firmware.
601              */
602             load_image_to_fw_cfg(fw_cfg,
603                                  FW_CFG_KERNEL_SIZE, FW_CFG_KERNEL_DATA,
604                                  info->kernel_filename,
605                                  try_decompressing_kernel);
606             load_image_to_fw_cfg(fw_cfg,
607                                  FW_CFG_INITRD_SIZE, FW_CFG_INITRD_DATA,
608                                  info->initrd_filename, false);
609 
610             if (info->kernel_cmdline) {
611                 fw_cfg_add_i32(fw_cfg, FW_CFG_CMDLINE_SIZE,
612                                strlen(info->kernel_cmdline) + 1);
613                 fw_cfg_add_string(fw_cfg, FW_CFG_CMDLINE_DATA,
614                                   info->kernel_cmdline);
615             }
616         }
617 
618         /* We will start from address 0 (typically a boot ROM image) in the
619          * same way as hardware.
620          */
621         return;
622     }
623 
624     if (arm_feature(&cpu->env, ARM_FEATURE_AARCH64)) {
625         primary_loader = bootloader_aarch64;
626         kernel_load_offset = KERNEL64_LOAD_ADDR;
627         elf_machine = EM_AARCH64;
628     } else {
629         primary_loader = bootloader;
630         kernel_load_offset = KERNEL_LOAD_ADDR;
631         elf_machine = EM_ARM;
632     }
633 
634     info->dtb_filename = qemu_opt_get(qemu_get_machine_opts(), "dtb");
635 
636     if (!info->secondary_cpu_reset_hook) {
637         info->secondary_cpu_reset_hook = default_reset_secondary;
638     }
639     if (!info->write_secondary_boot) {
640         info->write_secondary_boot = default_write_secondary;
641     }
642 
643     if (info->nb_cpus == 0)
644         info->nb_cpus = 1;
645 
646 #ifdef TARGET_WORDS_BIGENDIAN
647     big_endian = 1;
648 #else
649     big_endian = 0;
650 #endif
651 
652     /* We want to put the initrd far enough into RAM that when the
653      * kernel is uncompressed it will not clobber the initrd. However
654      * on boards without much RAM we must ensure that we still leave
655      * enough room for a decent sized initrd, and on boards with large
656      * amounts of RAM we must avoid the initrd being so far up in RAM
657      * that it is outside lowmem and inaccessible to the kernel.
658      * So for boards with less  than 256MB of RAM we put the initrd
659      * halfway into RAM, and for boards with 256MB of RAM or more we put
660      * the initrd at 128MB.
661      */
662     info->initrd_start = info->loader_start +
663         MIN(info->ram_size / 2, 128 * 1024 * 1024);
664 
665     /* Assume that raw images are linux kernels, and ELF images are not.  */
666     kernel_size = load_elf(info->kernel_filename, NULL, NULL, &elf_entry,
667                            &elf_low_addr, &elf_high_addr, big_endian,
668                            elf_machine, 1);
669     if (kernel_size > 0 && have_dtb(info)) {
670         /* If there is still some room left at the base of RAM, try and put
671          * the DTB there like we do for images loaded with -bios or -pflash.
672          */
673         if (elf_low_addr > info->loader_start
674             || elf_high_addr < info->loader_start) {
675             /* Pass elf_low_addr as address limit to load_dtb if it may be
676              * pointing into RAM, otherwise pass '0' (no limit)
677              */
678             if (elf_low_addr < info->loader_start) {
679                 elf_low_addr = 0;
680             }
681             if (load_dtb(info->loader_start, info, elf_low_addr) < 0) {
682                 exit(1);
683             }
684         }
685     }
686     entry = elf_entry;
687     if (kernel_size < 0) {
688         kernel_size = load_uimage(info->kernel_filename, &entry, NULL,
689                                   &is_linux, NULL, NULL);
690     }
691     /* On aarch64, it's the bootloader's job to uncompress the kernel. */
692     if (arm_feature(&cpu->env, ARM_FEATURE_AARCH64) && kernel_size < 0) {
693         entry = info->loader_start + kernel_load_offset;
694         kernel_size = load_image_gzipped(info->kernel_filename, entry,
695                                          info->ram_size - kernel_load_offset);
696         is_linux = 1;
697     }
698     if (kernel_size < 0) {
699         entry = info->loader_start + kernel_load_offset;
700         kernel_size = load_image_targphys(info->kernel_filename, entry,
701                                           info->ram_size - kernel_load_offset);
702         is_linux = 1;
703     }
704     if (kernel_size < 0) {
705         fprintf(stderr, "qemu: could not load kernel '%s'\n",
706                 info->kernel_filename);
707         exit(1);
708     }
709     info->entry = entry;
710     if (is_linux) {
711         uint32_t fixupcontext[FIXUP_MAX];
712 
713         if (info->initrd_filename) {
714             initrd_size = load_ramdisk(info->initrd_filename,
715                                        info->initrd_start,
716                                        info->ram_size -
717                                        info->initrd_start);
718             if (initrd_size < 0) {
719                 initrd_size = load_image_targphys(info->initrd_filename,
720                                                   info->initrd_start,
721                                                   info->ram_size -
722                                                   info->initrd_start);
723             }
724             if (initrd_size < 0) {
725                 fprintf(stderr, "qemu: could not load initrd '%s'\n",
726                         info->initrd_filename);
727                 exit(1);
728             }
729         } else {
730             initrd_size = 0;
731         }
732         info->initrd_size = initrd_size;
733 
734         fixupcontext[FIXUP_BOARDID] = info->board_id;
735 
736         /* for device tree boot, we pass the DTB directly in r2. Otherwise
737          * we point to the kernel args.
738          */
739         if (have_dtb(info)) {
740             /* Place the DTB after the initrd in memory. Note that some
741              * kernels will trash anything in the 4K page the initrd
742              * ends in, so make sure the DTB isn't caught up in that.
743              */
744             hwaddr dtb_start = QEMU_ALIGN_UP(info->initrd_start + initrd_size,
745                                              4096);
746             if (load_dtb(dtb_start, info, 0) < 0) {
747                 exit(1);
748             }
749             fixupcontext[FIXUP_ARGPTR] = dtb_start;
750         } else {
751             fixupcontext[FIXUP_ARGPTR] = info->loader_start + KERNEL_ARGS_ADDR;
752             if (info->ram_size >= (1ULL << 32)) {
753                 fprintf(stderr, "qemu: RAM size must be less than 4GB to boot"
754                         " Linux kernel using ATAGS (try passing a device tree"
755                         " using -dtb)\n");
756                 exit(1);
757             }
758         }
759         fixupcontext[FIXUP_ENTRYPOINT] = entry;
760 
761         write_bootloader("bootloader", info->loader_start,
762                          primary_loader, fixupcontext);
763 
764         if (info->nb_cpus > 1) {
765             info->write_secondary_boot(cpu, info);
766         }
767     }
768     info->is_linux = is_linux;
769 
770     for (cs = CPU(cpu); cs; cs = CPU_NEXT(cs)) {
771         ARM_CPU(cs)->env.boot_info = info;
772     }
773 }
774 
775 void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info *info)
776 {
777     CPUState *cs;
778 
779     info->load_kernel_notifier.cpu = cpu;
780     info->load_kernel_notifier.notifier.notify = arm_load_kernel_notify;
781     qemu_add_machine_init_done_notifier(&info->load_kernel_notifier.notifier);
782 
783     /* CPU objects (unlike devices) are not automatically reset on system
784      * reset, so we must always register a handler to do so. If we're
785      * actually loading a kernel, the handler is also responsible for
786      * arranging that we start it correctly.
787      */
788     for (cs = CPU(cpu); cs; cs = CPU_NEXT(cs)) {
789         qemu_register_reset(do_cpu_reset, ARM_CPU(cs));
790     }
791 }
792